Cell Cycle

Question 1

What is the function of cell division

Answer 1

Grow and repair damage

Question 2

In short, what is the cell cycle

Answer 2

A mother cell divides in to two daughters cells

Question 3

What are the four phases of the cell cycle

Answer 3

M-phase
G1-phase
S-phase
G2-phase

Question 4

What is the G0-phase

Answer 4

When the cell does not take part in the cell cycle

Question 5

In what phase does the cell enter the cell cycle

Answer 5

G1

Question 6

What happens in the S-phase

Answer 6

DNA Will be duplicated
(S > synthesis)

Question 7

What happens in the G2-phase

Answer 7

The cell prepares itself for division

Question 8

What happens in the M-phase

Answer 8

The division take place
(M > mitosis)

Question 9

What happens in the G1-phase

Answer 9

The cell grows

Question 10

What is the first check point of the cells cycle

Answer 10

Is the environment suitable for the division

Question 11

What is the second check point off the cell cycle

Answer 11

Was the DNA properly duplicated
Is the environment still good

Question 12

What is the third check point

Answer 12

Are all the chromosomes attached to the spindle

Question 13

In what phase are the checkpoints of the cell cycle

Answer 13

1: end of G1
2: beginning M
3: mid M (between metaphase and anaphase)

Question 14

What proteins regulate the checkpoints

Answer 14

Cyclins and cyclin-dependent kinase (Cdks)

Question 15

How is Cdk activated
(Cyclin kinase)

Answer 15

Phosphorylation

Question 16

How is Cdk inactivated
(Cyclin kinase)

Answer 16

Phosphorylation in two places

Question 17

How is Cyclin regulated

Answer 17

By protein production and breakdown

Question 18

How is Cyclin deactivated

Answer 18

By attaching to a ubiquitin flag
It wil than be broken down

Question 19

What types of Cyclins are there

Answer 19

G1/S- Cdk
S-Cdk
M-Cdk

Question 20

What happens with the Cyclins during mid M-phase

Answer 20

They are all broken down

Question 21

What is the first step of activation of G1-Cdk

Answer 21

Mitogen attaches on a receptor

Question 22

What wil the receptor, with mitogen attached to it, activate

Answer 22

Ras protein

Question 23

How will MAP kinase activate G1-Cdk

Answer 23

Immediate early gene expression > gene regulatory protein > delayed-response gene expression > G1-Cdk

Question 24

What will G1-Cdk phosphorylate

Answer 24

Rb protein, it becomes active

Question 25

What happens if Rb protein is activated

Answer 25

It will let go of E2F protein

Question 26

What does E2F protein do

Answer 26

Triggers S-phase gene transcription

Question 27

What proteins are being produced by S-phase gene transcription

Answer 27

G1/S-Cyclin (Cyclin E) S-Cyclin (Cyclin A)

Question 28

On what have the g1/S and S Cyclin positive feedback

Answer 28

E2F protein

Question 29

What proteins divides DNA in two strands

Answer 29

Helicase

Question 30

On what does ORC (origin recognition complex) bind

Answer 30

Origins in the DNA (in the G1 phase)

Question 31

Which two proteins does ORC recruit

Answer 31

Cdc6 helicase

Question 32

What do Cdc6 and Helicase create

Answer 32

Prereplicative complex (pre-RC)

Question 33

Why can’t Helicase open the DNA in the G1 phase

Answer 33

Because it’s bound to Cdc6

Question 34

What does S-Cdk to Cdc6

Answer 34

It phosphates it so it loses binding to Helicase

Question 35

How are more copies of the DNA prevented

Answer 35

ORC will stay bound and phosphorylated

Question 36

What happens if there is a problem with the cell cycle or with apoptose (Disbalans)

Answer 36

Tumors

Question 37

What is a risk factor for tumors

Answer 37

P53

Question 38

How is p53 activated

Answer 38

Damaged DNA > AMT/ATR kinase activation > Chk1/2 kinase activation > phosphorylation of p53 ( loses Mdm2) > active p53 > makes RNA of p21

Question 39

What does p21 to

Answer 39

P21 mRNA activates translation of Cdk inhibitor proteins (p21) which deactivated G1/S-Cdk

Question 40

Why is a mutation in P53 bad

Answer 40

Bad cell (with damaged DNA) will enter the cell cycle

Question 41

What is an other risk factor for the cell cycle

Answer 41

DNA viruses

Question 42

What does a DNA virus do Name 2

Answer 42

Produces E7 (looks like E2F) > binds to Rb > the real E2F does not get inactive but keeps working Produces E6 > binds to p53 > so on

Question 43

What determines the speed of the cell cycle

Answer 43

Regulation of Cyclin/Cdk activity